Process control for enhanced L-phenylalanine production using different recombinant Escherichia coli strains

Area of Science:

• Biotechnology
• Metabolic Engineering
• Microbial Fermentation

Background:

• L-phenylalanine (L-Phe) is an essential amino acid with significant industrial applications.
• Recombinant Escherichia coli (E. coli) are widely used for microbial production of L-Phe.
• Optimizing fermentation parameters is crucial for maximizing L-Phe yield and productivity.

Purpose of the Study:

• To develop and evaluate a novel fed-batch fermentation strategy for L-Phe production using recombinant E. coli.
• To investigate the impact of on-line control of glucose and tyrosine on L-Phe production.
• To compare L-Phe production performance between a wild-type and a feedback-resistant mutant strain.

Main Methods:

• Utilized a fed-batch fermentation approach with recombinant E. coli strains.
• Implemented on-line monitoring and control for key fermentation parameters: glucose and tyrosine.
• Employed two E. coli production strains: one with tyrosine feedback-resistant aroF(fbr) and one with wild-type aroF(wt).

Main Results:

• The wild-type aroF(wt) strain achieved higher final L-Phe titers (34 g/L) compared to the aroF(fbr) strain (28 g/L) under tyrosine control.
• On-line glucose control identified an optimal glucose concentration of 5 g/L, balancing carbon supply and preventing acetate by-product formation.
• The developed process demonstrated suitability for both lab-scale and pilot-scale bioreactors.

Conclusions:

• On-line control of tyrosine and glucose enables optimized L-Phe production in recombinant E. coli.
• The wild-type aroF(wt) strain, with tyrosine control, is superior for L-Phe production over the feedback-resistant mutant.
• This fed-batch strategy offers a robust and scalable approach for industrial L-Phe manufacturing.